Hydrogen, which is a material having most light and simple structure on earth, has physical and chemical characteristic of about six bn times of laminar flame velocity and about three times of lower heating value compared with gasoline. Accordingly, during combusting by properly mixing gasoline and hydrogen, combustion speed and combustion stability may be increased to improve thermal efficiency by expanding lean boundary or increasing supply amount of exhaust gas recirculation.
Meanwhile, a fuel reformer is a system generating hydrogen. The hydrogen is generated by reacting separate gasoline fuel supplied to the reformer with a catalyst in the reformer using thermal energy of high temperature exhaust gas exhausted from an engine.
The reforming catalyst is heated only by the thermal energy of the exhaust gas supplied to the fuel reformer. However, in the low speed, low load operation region where the exhaust gas temperature flowing into the fuel reformer is low, it is difficult to sufficiently ensure the activation temperature of the fuel reforming catalyst. Therefore, there is a problem that the reforming operation range is limited and the reforming efficiency is lowered.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.